Outback hospital is after transport for many passengers (4)
I believe the answer is:
bush
'outback' is the definition.
(I've seen this in another clue)
'hospital is after transport for many passengers' is the wordplay.
'hospital' becomes 'H' (abbreviation for hospital on maps).
'is after' is a charade indicator (letters next to each other).
'transport for many passengers' becomes 'bus' (public transport).
'h' after 'bus' is 'BUSH'.
(Other definitions for bush that I've seen before include "Rural African" , "Two US presidents" , "Low, woody plant" , "Shrub; metal lining" , "metal sleeve used in drilling" .)